Re: Setting the buffer size when using the Default Output AudioUnit
Re: Setting the buffer size when using the Default Output AudioUnit
- Subject: Re: Setting the buffer size when using the Default Output AudioUnit
- From: Lionel Woog <email@hidden>
- Date: Tue, 18 Feb 2003 16:08:58 -0500
Hi,
Threaded operations work, but without being superuser, I cannot set the
thread priority above (below) 0, and this is inadequate for audio
operations. The slightest window move or scrolling will disrupt the audio,
even though the decoder consumes no more than 20% of the CPU on a 450Mhz G4.
How can I get a high priority thread for my decoder.
Thanks,
Lionel
>
Lionel,
>
>
Although you can change the device frame size as Luke indicates below,
>
to solve your problem I would recommend buffering ahead with the
>
decompression in a separate thread. I think trying to solve your problem
>
by increasing the buffer size will just get you into trouble.
>
>
Chris Rogers
>
Core Audio
>
Apple Computer
>
>
>
>
> In the <AudioUnit/AudioUnit.h> API's, get the AudioDeviceID of your
>
> output unit (kAudioOutputUnitProperty_CurrentDevice.)
>
>
>
> Armed with that, use the <CoreAudio/CoreAudio.h> API's set the
>
> kAudioDevicePropertyBufferFrameSize on that AudioDeviceID to 4096,
>
> being sure that 4096 falls in the range returned by
>
> kAudioDevicePropertyBufferFrameSizeRange for that device.
>
>
>
> On Tuesday, February 18, 2003, at 08:36 AM, Lionel Woog wrote:
>
>
>
>> Hi,
>
>>
>
>> What can I do to change the number of frames requested by the rendering
>
>> callback of the default output unit to be 4096 instead of 512.
>
>>
>
>> At 512, my audio will not play smoothly, as I decompress data in 8192 frames
>
>> increments and this requires more CPU than can be done in 512/44100th of a
>
>> second.
>
>>
>
>> I can get smooth playback by directly hooking up a rendered to the hardware
>
>> audio device (and setting the buffer size appropriately), but doing so
>
>> prevents me from having more than one player going at a time.
>
>>
>
>> Thanks for any help,
>
>>
>
>> Lionel
>
>>
>
>> --
>
>> Lionel Woog, Ph.D.
>
>> CTO
>
>> Adapted Wave Technologies, Inc.
>
>> email: email@hidden
>
>> phone: 212-645-0670
>
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>
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>
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>
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--
Lionel Woog, Ph.D.
CTO
Adapted Wave Technologies, Inc.
email: email@hidden
phone: 212-645-0670
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